ANSI/ASHRAE Standard 55-2004
(Supersedes ANSI/ASHRAE Standard 55-1992)
Thermal
Environmental
Conditions for
Human Occupancy
Approved by the ASHRAE Standards Committee on January 24, 2004; by the ASHRAE Board of Directors on January 29, 2004; and by the American National Standards
Institute on April 16, 2004.
ASHRAE Standards are scheduled to be updated on a
five-year cycle; the date following the standard number is
the year of ASHRAE Board of Directors approval. The
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©Copyright 2004 American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc.
ISSN 1041-2336
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ASHRAE Standard Project Committee 55
Cognizant TC: TC 2.1, Physiology and Human Environment
SPLS Liaison: Frank E. Jakob
Wayne A. Dunn, Chair*
Gail S. Brager, Vice-Chair*
Gaetano Alfano
Larry G. Berglund
Karl A. Brown
Daniel R. Clark
Joseph J. Deringer*
Clifford C. Federspiel
Jaap J. Hogeling
Daniel Int-Hout, III* (Chair, 1999-2001)
Byron W. Jones
Joseph N. Knapp
Alison G. Kwok*
Hal Levin*
Arsen K. Melikov
Bjarne W. Olesen* (Chair, 1995-1998)
Nigel A. Oseland
Nicholas B. Rajkovich*
Gary Raw
David G. Scheatzle*
Dipak J. Shah
Peter Simmonds*
Jerry M. Sipes*
Elia M. Sterling*
Benjamin P. Sun*
Steven T. Taylor*
Shin-Ichi Tanabe
Robert W. Tinsley*
Jorn Toftum*
Stephen C. Turner*
James E. Woods
*Denotes members of voting status when the document was approved for publication
ASHRAE STANDARDS COMMITTEE 2003-2004
Frank E. Jakob
Stephen D. Kennedy
David E. Knebel
Frederick H. Kohloss
Merle F. McBride
Mark P. Modera
Cyrus H. Nasseri
Gideon Shavit
David R. Tree
Thomas H. Williams
James E. Woods
Ross D. Montgomery, BOD ExO
Kent W. Peterson, CO
Van D. Baxter, Chair
Davor Novosel, Vice-Chair
Donald B. Bivens
Dean S. Borges
Paul W. Cabot
Charles W. Coward, Jr.
Hugh F. Crowther
Brian P. Dougherty
Hakim Elmahdy
Matt R. Hargan
Richard D. Hermans
John F. Hogan
Claire B. Ramspeck, Manager of Standards
SPECIAL NOTE
This American National Standard (ANS) is a national voluntary consensus standard developed under the auspices of the American
Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Consensus is defined by the American National Standards
Institute (ANSI), of which ASHRAE is a member and which has approved this standard as an ANS, as “substantial agreement reached
by directly and materially affected interest categories. This signifies the concurrence of more than a simple majority, but not necessarily
unanimity. Consensus requires that all views and objections be considered, and that an effort be made toward their resolution.”
Compliance with this standard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation.
ASHRAE obtains consensus through participation of its national and international members, associated societies, and public
review.
ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The
Project Committee Chair and Vice-Chair must be members of ASHRAE; while other committee members may or may not be ASHRAE
members, all must be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interests
on all Project Committees.
The Manager of Standards of ASHRAE should be contacted for:
a. interpretation of the contents of this Standard,
b. participation in the next review of the Standard,
c. offering constructive criticism for improving the Standard,
d. permission to reprint portions of the Standard.
DISCLAIMER
ASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available
information and accepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or
performance of any products, components, or systems tested, installed, or operated in accordance with ASHRAE’s Standards
or Guidelines or that any tests conducted under its Standards or Guidelines will be nonhazardous or free from risk.
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stated or implied, that the product has been approved by ASHRAE.
CONTENTS
ANSI/ASHRAE Standard 55-2004
Thermal Environmental Conditions for Human Occupancy
SECTION
PAGE
Foreword ................................................................................................................................................................... 2
1 Purpose .......................................................................................................................................................... 2
2 Scope ............................................................................................................................................................. 2
3 Definitions....................................................................................................................................................... 2
4 General Requirements ................................................................................................................................... 3
5 Conditions that Provide Thermal Comfort ...................................................................................................... 4
6 Compliance................................................................................................................................................... 11
7 Evaluation of the Thermal Environment ....................................................................................................... 12
8 References ................................................................................................................................................... 14
Normative Appendix A: Activity Levels.............................................................................................................. 15
Normative Appendix B: Clothing Insulation....................................................................................................... 16
Informative Appendix C: Acceptable Approximation for Operative Temperature ............................................... 20
Normative Appendix D: Computer Program for Calculation of PMV-PPD ........................................................ 21
Informative Appendix E: Thermal Environment Survey...................................................................................... 23
Informative Appendix F: Bibliography ................................................................................................................ 25
© Copyright 2004 American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc.
1791 Tullie Circle NE
Atlanta, GA 30329
www.ashrae.org
All rights reserved.
(This foreword is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject
to public review or a consensus process.)
FOREWORD
Standard 55-2004, “Thermal Environmental Conditions
for Human Occupancy,” is a revision of Standard 55-1992.
The standard specifies conditions in which a specified fraction
of the occupants will find the environment thermally acceptable. The revision is a consensus standard that has undergone
public and ASHRAE review; it incorporates the relevant
research and experience gained since the 1992 revision. Such
changes include the addition of the PMV/PPD calculation
methods and the concept of adaptation. The standard is
intended for use in design, commissioning, and testing of
buildings and other occupied spaces and their HVAC systems
and for the evaluation of thermal environments. Because it is
not possible to prescribe the metabolic rate of occupants, and
because of variations in occupant clothing levels, operating
setpoints for buildings cannot be practically mandated by this
standard.
The designer may choose, in agreement with the owner or
owner’s representative (e.g., owner’s agent, developer, or
equivalent), the level of thermal comfort and appropriate
exceedance. The selected design criteria will influence the
HVAC system design and may also influence the building
design. This standard may also be used for evaluation of existing thermal environments in buildings, during experimental
conditions, and for the development and testing of products.
This standard is in close agreement with ISO Standards
77261 and 7730.2
1. PURPOSE
The purpose of this standard is to specify the combinations of indoor thermal environmental factors and personal
factors that will produce thermal environmental conditions
acceptable to a majority of the occupants within the space.
2. SCOPE
2.1 The environmental factors addressed in this standard are
temperature, thermal radiation, humidity, and air speed; the
personal factors are those of activity and clothing.
2.2 It is intended that all of the criteria in this standard be
applied together since comfort in the indoor environment is
complex and responds to the interaction of all of the factors
that are addressed.
2.3 This standard specifies thermal environmental conditions acceptable for healthy adults at atmospheric pressure
equivalent to altitudes up to 3000 m (10,000 ft) in indoor
spaces designed for human occupancy for periods not less
than 15 minutes.
2.4 This standard does not address such nonthermal environmental factors as air quality, acoustics, and illumination or
other physical, chemical, or biological space contaminants
that may affect comfort or health.
2
3. DEFINITIONS
adaptive model: a model that relates indoor design temperatures or acceptable temperature ranges to outdoor meteorological or climatalogical parameters.
air speed: the rate of air movement at a point, without regard
to direction.
clo: a unit used to express the thermal insulation provided by
garments and clothing ensembles, where 1 clo = 0.155 m2 °C/
W (0.88 ft2·h·°F/Btu).
comfort, thermal: that condition of mind which expresses
satisfaction with the thermal environment and is assessed by
subjective evaluation.
draft: the unwanted local cooling of the body caused by air
movement.
draft rate (DR): percentage of people predicted to be dissatisfied due to draft.
environment, thermal: the characteristics of the environment
that affect a person's heat loss.
environment, acceptable thermal: an environment that a
substantial majority of the occupants would find thermally
acceptable.
garment: a single piece of clothing.
humidity ratio: the ratio of the mass of water vapor to the mass
of dry air in a given volume.
humidity, relative (RH): the ratio of the partial pressure (or
density) of the water vapor in the air to the saturation pressure
(or density) of water vapor at the same temperature and the
same total pressure.
insulation, clothing/ensemble (Icl ): the resistance to sensible
heat transfer provided by a clothing ensemble. Expressed in
clo units. Note: The definition of clothing insulation relates to
heat transfer from the whole body and, thus, also includes the
uncovered parts of the body, such as head and hands.
insulation, garment (Iclu ): the increased resistance to sensible heat transfer obtained from adding an individual garment
over the nude body. Expressed in clo units.
met: a unit used to describe the energy generated inside the
body due to metabolic activity, defined as 58.2 W/m2 (18.4
Btu/h·ft2), which is equal to the energy produced per unit
surface area of an average person, seated at rest. The surface
area of an average person is 1.8 m2 (19 ft2).
metabolic rate (M): the rate of transformation of chemical
energy into heat and mechanical work by metabolic activities
within an organism, usually expressed in terms of unit area of
the total body surface. In this standard, this rate is expressed
in met units.
ANSI/ASHRAE STANDARD 55-2004
naturally conditioned spaces, occupant controlled: those
spaces where the thermal conditions of the space are regulated
primarily by the opening and closing of windows by the occupants.
temperature, plane radiant (tpr ): the uniform temperature of
an enclosure in which the incident radiant flux on one side of
a small plane element is the same as in the existing environment.
neutrality, thermal: the indoor thermal index value corresponding with a mean vote of neutral on the thermal sensation
scale.
time constant: the time for a measuring sensor to reach 63%
of the final value after a step change.
percent dissatisfied (PD): percentage of people predicted to
be dissatisfied due to local discomfort.
turbulence intensity (Tu): the ratio of the standard deviation of the air speed (SDv) to the mean air speed (v). Turbulence intensity may also be expressed in percent (i.e., Tu =
[SDv / va] · 100).
predicted mean vote (PMV): an index that predicts the mean
value of the votes of a large group of persons on the sevenpoint thermal sensation scale.
predicted percentage of dissatisfied (PPD): an index that
establishes a quantitative prediction of the percentage of thermally dissatisfied people determined from PMV.
radiant temperature asymmetry: the difference between the
plane radiant temperature of the two opposite sides of a small
plane element.
response time (90%): the time for a measuring sensor to reach
90% of the final value after a step change. For a measuring
system that includes only one exponential time-constant function, the 90% response time equals 2.3 times the “time
constant.”
sensation, thermal: a conscious feeling commonly graded
into the categories cold, cool, slightly cool, neutral, slightly
warm, warm, and hot; it requires subjective evaluation.
step change: an incremental change in a variable, either by
design or as the result of an interval between measurement;
typically, an incremental change in a control setpoint.
temperature, air (ta ): the temperature of the air surrounding
the occupant.
temperature, dew point (tdp ): the temperature at which moist
air becomes saturated (100% relative humidity) with water
vapor (psdp = pa) when cooled at constant pressure.
temperature, mean monthly outdoor air (ta(out) ): when used
as input variable in Figure 5.3.1 for the adaptive model, this
temperature is based on the arithmetic average of the mean
daily minimum and mean daily maximum outdoor (dry-bulb)
temperatures for the month in question.
temperature, mean radiant (tr ): the uniform surface temperature of an imaginary black enclosure in which an occupant
would exchange the same amount of radiant heat as in the
actual nonuniform space; see Section 7.2 for information on
measurement positions.
temperature, operative (to ): the uniform temperature of an
imaginary black enclosure in which an occupant would
exchange the same amount of heat by radiation plus convection as in the actual nonuniform environment; see Section 7.2
for information on body position within the imaginary enclosure.
ANSI/ASHRAE STANDARD 55-2004
water vapor pressure (pa ): the pressure that the water vapor
would exert if it alone occupied the volume occupied by the
humid air at the same temperature.
water vapor pressure, saturated dewpoint (psdp ): the water
vapor pressure at the saturation temperature corresponding to
the reference pressure and without any liquid phase.
velocity, mean (va ): an average of the instantaneous air velocity over an interval of time.
velocity, standard deviation (SDv ): a measure of the scatter of
the instantaneous air velocity around the mean air velocity in
a frequency distribution, defined as the square root of the
arithmetic average of a set of square values of the difference
between the instantaneous air velocity and the mean air velocity. The standard deviation is based on individual values of air
speed that represent an average over no more than two seconds
each.
zone, occupied: the region normally occupied by people
within a space, generally considered to be between the floor
and 1.8 m (6 ft) above the floor and more than 1.0 m (3.3 ft)
from outside walls/windows or fixed heating, ventilating, or
air-conditioning equipment and 0.3 m (1 ft) from internal
walls.
4. GENERAL REQUIREMENTS
Use of this standard is specific to the space being considered and the occupants of that space. Any application of this
standard must specify the space to which it applies or the locations within that space to which it applies, if not to the entire
space. Any application of this standard must identify the occupants (who must have a residency of more than 15 minutes in
the space) to which it applies.
The activity and clothing of the occupants must be considered in applying this standard. When there are substantial
differences in physical activity and/or clothing for occupants
of a space, these differences must be considered.
It may not be possible to achieve an acceptable thermal
environment for all occupants of a space due to individual
differences, including activity and/or clothing. If the requirements are not met for some known set of occupants, then these
occupants must be identified.
3
The thermal environmental conditions required for
comfort are determined according to Section 5.2 or Section 5.3
of this standard. Any application of this standard must clearly
state which of these sections is used. Additionally, all requirements of the applicable section, 5.2 or 5.3, must be met.
5. CONDITIONS THAT PROVIDE
THERMAL COMFORT
Introduction
Thermal comfort is that condition of mind which
expresses satisfaction with the thermal environment. Because
there are large variations, both physiologically and psychologically, from person to person, it is difficult to satisfy everyone
in a space. The environmental conditions required for comfort
are not the same for everyone. However, extensive laboratory
and field data have been collected that provide the necessary
statistical data to define conditions that a specified percentage
of occupants will find thermally comfortable. Section 5 of this
standard is used to determine the thermal environmental
conditions in a space that are necessary to achieve acceptance
by a specified percentage of occupants of that space.
There are six primary factors that must be addressed when
defining conditions for thermal comfort. A number of other,
secondary factors affect comfort in some circumstances. The
six primary factors are listed below. Complete descriptions of
these factors are presented in Section 5.4 and Appendices A
and B.
5.1
1.
Metabolic rate
2.
Clothing insulation
3.
Air temperature
4.
Radiant temperature
5.
Air speed
6.
Humidity
All six of these factors may vary with time. However, this
standard only addresses thermal comfort in a steady state (with
some limited specifications for temperature variations with
time in Section 5.2.5). As a result, people entering a space that
meets the requirements of this standard may not immediately
find the conditions comfortable if they have experienced
different environmental conditions just prior to entering the
space. The effect of prior exposure or activity may affect
comfort perceptions for approximately one hour.
Factors 2 through 6 may be nonuniform over an occupant's body, and this nonuniformity may be an important
consideration in determining thermal comfort. Nonuniformity
is addressed in Section 5.2.4.
The vast majority of the available thermal comfort data
pertains to sedentary or near sedentary physical activity levels
typical of office work. This standard is intended primarily for
these conditions. However, it may also be used to determine
appropriate environmental conditions for moderately elevated
activity. It does not apply to sleeping or bed rest. The body of
available data does not contain significant information regarding the comfort requirements of children, the disabled, or the
infirm. However, the information in this standard can often be
applied to these types of occupants if it is applied judiciously
4
to groups of occupants such as are found in classroom situations.
Section 5.2 contains the methodology that shall be used
for most applications. However, the conditions required for
thermal comfort in spaces that are naturally conditioned are
not necessarily the same as those conditions required for other
indoor spaces. Field experiments have shown that in naturally
conditioned spaces, where occupants have control of operable
windows, the subjective notion of comfort is different because
of different thermal experiences, availability of control, and
resulting shifts in occupant expectations. Section 5.3 specifies
criteria required for a space to be considered naturally conditioned. The methods of Section 5.3 may, as an option, be
applied to spaces that meet these criteria. The methods of
Section 5.3 may not be applied to other spaces.
Section 5.4 describes in some detail variables that must be
clearly understood in order to use the methods of Section 5
effectively.
5.2 Method for Determining Acceptable Thermal
Conditions in Occupied Spaces
When Section 5.2 is used to determine the requirements
for thermal comfort, the requirements of all subsections—
5.2.1, 5.2.2, 5.2.3, 5.2.4, and 5.2.5—must be met. This standard recommends a specific percentage of occupants that
constitutes acceptability and values of the thermal environment associated with this percentage.
5.2.1 Operative Temperature. For given values of
humidity, air speed, metabolic rate, and clothing insulation, a
comfort zone may be determined. The comfort zone is defined
in terms of a range of operative temperatures that provide
acceptable thermal environmental conditions or in terms of
the combinations of air temperature and mean radiant temperature that people find thermally acceptable.
This section describes methods that may be used to determine temperature limits for the comfort zone. Section 5.2.1.1
uses a simplified graphical method for determining the
comfort zone that may be used for many typical applications.
Section 5.2.1.2 uses a computer program based on a heat
balance model to determine the comfort zone for a wider range
of applications. For a given set of conditions, the results from
the two methods are consistent, and either method may be used
as long as the criteria outlined in the respective section are met.
See Appendix C and the 2001 ASHRAE Handbook—
Fundamentals,3 Chapter 8, for procedures to calculate operative temperature. Dry-bulb temperature may be used as a
proxy for operative temperature under certain conditions
described in Appendix C.
5.2.1.1 Graphical Method for Typical Indoor Environments. The method in this section may be applied to
spaces where the occupants have activity levels that result in
metabolic rates between 1.0 met and 1.3 met and where clothing is worn that provides between 0.5 clo and 1.0 clo of thermal insulation. See Appendix A for estimation of metabolic
rates and Appendix B for estimation of clothing insulation.
Most office spaces fall within these limitations.
The range of operative temperatures presented in Figure
5.2.1.1 are for 80% occupant acceptability. This is based on a
10% dissatisfaction criteria for general (whole body) thermal
ANSI/ASHRAE STANDARD 55-2004
Figure 5.2.1.1 Acceptable range of operative temperature and humidity for spaces that meet the criteria specified in Section 5.2.1.1.
comfort based on the PMV-PPD index, plus an additional 10%
dissatisfaction that may occur on average from local (partial
body) thermal discomfort. Appendix D provides a list of
inputs and outputs used in the PMV/PPD computer program to
generate these graphs.
Figure 5.2.1.1 specifies the comfort zone for environments that meet the above criteria and where the air speeds are
not greater than 0.20 m/s (40 ft/min). Two zones are shown—
one for 0.5 clo of clothing insulation and one for 1.0 clo of
insulation. These insulation levels are typical of clothing worn
when the outdoor environment is warm and cool, respectively.
The operative temperature range allowed for intermediate
values of clothing insulation may be determined by linear
interpolation between the limits for 0.5 clo and 1.0 clo, using
the following relationships:
Tmin, Icl = [(Icl – 0.5 clo) Tmin, 1.0 clo
+ (1.0 clo – Icl) Tmin, 0.5clo] / 0.5 clo
Tmax, Icl = [(Icl – 0.5 clo) Tmax, 1.0 clo
+ (1.0 clo – Icl) Tmax, 0.5clo] / 0.5 clo
where
Tmax, Icl = upper operative temperature limit for clothing
insulation Icl,
Tmin, Icl
= lower operative temperature limit for clothing
insulation Icl, and
Icl
= thermal insulation of the clothing in question
(clo).
Air speeds greater than 0.20 m/s (40 ft/min) may be used
to increase the upper operative temperature limit for the
comfort zone in certain circumstances. Section 5.2.3 describes
these adjustments and specifies the criteria required for such
adjustments.
5.2.1.2 Computer Model Method for General Indoor
Application. The method in this section may be applied to
spaces where the occupants have activity levels that result in
average metabolic rates between 1.0 met and 2.0 met and
where clothing is worn that provides 1.5 clo or less of thermal
ANSI/ASHRAE STANDARD 55-2004
Figure 5.2.1.2 Predicted percentage dissatisfied (PPD) as a
function of predicted mean vote (PMV).
insulation. See Appendix A for estimation of metabolic rates
and Appendix B for estimation of clothing insulation.
The ASHRAE thermal sensation scale, which was developed for use in quantifying people's thermal sensation, is
defined as follows:
+3 hot
+2 warm
+1 slightly warm
0 neutral
–1 slightly cool
–2 cool
–3 cold
The predicted mean vote (PMV) model uses heat balance
principles to relate the six key factors for thermal comfort
listed in Section 5.1 to the average response of people on the
above scale. The PPD (predicted percentage of dissatisfied)
index is related to the PMV as defined in Figure 5.2.1.2. It is
based on the assumption that people voting +2, +3, –2, or –3
5
TABLE 5.2.1.2
Acceptable Thermal Environment for General Comfort
PPD
PMV Range
< 10
-0.5 < PMV < + 0.5
on the thermal sensation scale are dissatisfied, and the simplification that PPD is symmetric around a neutral PMV.
Table 5.2.1.2 defines the recommended PPD and PMV
range for typical applications. This is the basis for the graphical method in Section 5.2.1.1.
The comfort zone is defined by the combinations of air
temperature and mean radiant temperature for which the PMV
is within the recommended limits specified in Table 5.2.1.2.
The PMV model is calculated with the air temperature and
mean radiant temperature in question along with the applicable metabolic rate, clothing insulation, air speed, and humidity. If the resulting PMV value generated by the model is
within the recommended range, the conditions are within the
comfort zone.
Use of the PMV model in this standard is limited to air
speeds not greater than 0.20 m/s (40 fpm). Air speeds greater
than 0.20 m/s (40 ft/min) may be used to increase the upper
temperature limits of the comfort zone in certain circumstances. Section 5.2.3 describes these adjustments and specifies the criteria required for such adjustments. The
adjustments in Section 5.2.3 are with respect to the upper limit
of the comfort zone determined with the PMV model using an
air speed of 0.20 m/s (40 fpm).
There are several computer codes available that predict
PMV-PPD. The computer code in Appendix D is to be used
with this standard.4 If any other version is used, it is the user's
responsibility to verify and document that the version used
yields the same results as the code in Appendix D for the
conditions for which it is applied.
5.2.2 Humidity Limits. Systems designed to control
humidity shall be able to maintain a humidity ratio at or
below 0.012, which corresponds to a water vapor pressure of
1.910 kPa (0.277 psi) at standard pressure or a dew-point
temperature of 16.8°C (62.2°F).
There are no established lower humidity limits for thermal
comfort; consequently, this standard does not specify a minimum humidity level. However, non-thermal comfort factors,
such as skin drying, irritation of mucus membranes, dryness of
the eyes, and static electricity generation, may place limits on
the acceptability of very low humidity environments.
5.2.3 Elevated Air Speed. Precise relationships between
increased air speed and improved comfort have not been
established. However, this standard allows elevated air speed
to be used to increase the maximum temperature for acceptability if the affected occupants are able to control the air
speed. The amount that the temperature may be increased is
shown in Figure 5.2.3. The combinations of air speed and
temperature defined by the lines in this figure result in the
same heat loss from the skin. The reference point for these
curves is the upper temperature limit of the comfort zone
(PMV = +0.5) and 0.20 m/s (40 fpm) of air speed. This figure
applies to a lightly clothed person (with clothing insulation
between 0.5 clo and 0.7 clo) who is engaged in near sedentary
physical activity (with metabolic rates between 1.0 met and
1.3 met).
6
Figure 5.2.3 Air speed required to offset increased
temperature.
The indicated increase in temperature pertains to both the
mean radiant temperature and the air temperature. That is,
both temperatures increase by the same amount with respect to
the starting point. When the mean radiant temperature is low
and the air temperature is high, elevated air speed is less effective at increasing heat loss. Conversely, elevated air speed is
more effective at increasing heat loss when the mean radiant
temperature is high and the air temperature is low. Thus, the
curve in Figure 5.2.3 that corresponds to the relative difference
between air temperature and mean radiant temperature must
be used. It is acceptable to interpolate between curves for
intermediate differences.
Elevated air speed may be used to offset an increase in the
air temperature and the mean radiant temperature, but not by
more than 3.0°C (5.4°F) above the values for the comfort zone
without elevated air speed. The required air speed may not be
higher than 0.8 m/s (160 fpm). Large individual differences
exist between people with regard to the preferred air speed.
Therefore, the elevated air speed must be under the direct
control of the affected occupants and adjustable in steps no
greater than 0.15 m/s (30 fpm). The benefits that can be gained
by increasing air speed depend on clothing and activity. Due
to increases in skin wettedness, the effect of increased speed
is greater with elevated activity than with sedentary activity.
Due to increased amounts of exposed skin, the effect of
increased air speed is greater with lighter clothing. Thus,
Figure 5.2.3 is conservative for activity levels above 1.3 met
and/or for clothing insulation less than 0.5 clo and may be
applied in these circumstances.
Due to increased body coverage, the effect of increased
air speed is less with higher levels of clothing insulation. Thus,
Figure 5.2.3 will underestimate the required air speed for
clothing insulation greater than 0.7 clo and shall not be applied
in these circumstances.
5.2.4 Local Thermal Discomfort. The local thermal discomfort caused by a vertical air temperature difference
between the feet and the head by an asymmetric radiant field,
by local convective cooling (draft), or by contact with a hot or
cold floor must be considered in determining conditions for
acceptable thermal comfort. Requirements for these factors
are specified in this section.
ANSI/ASHRAE STANDARD 55-2004
TABLE 5.2.4
Percentage Dissatisfied Due to Local Discomfort from Draft (DR) or Other Sources (PD)
DR Due to Draft
PD Due to Vertical Air
Temperature Difference
PD Due to Warm or Cool Floors
PD Due to Radiant
Asymmetry
< 20%
< 5%
< 10%
< 5%
TABLE 5.2.4.1
Allowable Radiant Temperature Asymmetry
Radiant Temperature Asymmetry °C (°F)
Warm Ceiling
Cool Wall
Cool Ceiling
Warm Wall
< 5 (9.0)
< 10 (18.0)
< 14 (25.2)
< 23 (41.4)
The requirements specified in this section apply to a
lightly clothed person (with clothing insulation between 0.5
clo and 0.7 clo) engaged in near sedentary physical activity
(with metabolic rates between 1.0 met and 1.3 met). With
higher metabolic rates and/or with more clothing insulation,
people are less thermally sensitive and, consequently, the risk
of local discomfort is lower. Thus, the requirements of this
section may also be used for metabolic rates greater than 1.3
met and with clothing insulation greater than 0.7 clo and will
be conservative. People are more sensitive to local discomfort
when the whole body is cooler than neutral and less sensitive
to local discomfort when the whole body is warmer than
neutral. The requirements of this section are based on environmental temperatures near the center of the comfort zone.
These requirements apply to the entire comfort zone, but they
may be conservative for conditions near the upper temperature
limits of the comfort zone and may underestimate acceptability at the lower temperature limits of the comfort zone.
Table 5.2.4 specifies the expected percent dissatisfied
(PD) for each source of local thermal discomfort described in
Sections 5.2.4.1 through 5.2.4.4. The criteria for all sources of
local thermal discomfort must be met simultaneously at the
levels specified for an environment to meet the requirements
of this standard.
5.2.4.1 Radiant Temperature Asymmetry. The thermal radiation field about the body may be nonuniform due to
hot and cold surfaces and direct sunlight. This asymmetry
may cause local discomfort and reduce the thermal acceptability of the space. In general, people are more sensitive to
asymmetric radiation caused by a warm ceiling than that
caused by hot and cold vertical surfaces. Figure 5.2.4.1 gives
the predicted percentage of dissatisfied occupants as a function of the radiant temperature asymmetry caused by a warm
ceiling, a cool wall, a cool ceiling, or a warm wall.
The limits for radiant temperature asymmetry are specified in Table 5.2.4.1. Alternatively, Figure 5.4.2.1 may be used
in conjunction with the PD limits from Table 5.2.4 to determine the allowable radiant asymmetry.
5.2.4.2 Draft. Draft is unwanted local cooling of the
body caused by air movement. Draft sensation depends on the
air speed, the air temperature, the turbulence intensity, the
activity, and the clothing. Sensitivity to draft is greatest where
the skin is not covered by clothing, especially the head region
comprising the head, neck, and shoulders and the leg region
ANSI/ASHRAE STANDARD 55-2004
Figure 5.2.4.1
Local thermal discomfort caused by radiant
asymmetry.
comprising the ankles, feet, and legs. The requirements in this
section are based on sensitivity to draft in the head region with
airflow from behind and may be conservative for some locations on the body and for some directions of airflow.
The maximum allowable air speed is specified in Figure
5.2.4.2 as a function of air temperature and turbulence intensity. Alternatively, the following equation may be used for
determining the maximum allowable air speed. The predicted
percentage of people dissatisfied due to annoyance by draft
(DR) is given by
DR = ([34-ta] * [v-0.05]0.62) * (0.37 * v * Tu + 3.14) ,
where
DR =
predicted percentage of people dissatisfied due to
draft;
ta
= local air temperature, °C;
v
= local mean air speed, m/s, based on va, the mean
velocity; and
Tu
= local turbulence intensity, %.
For ta (°F), v in fpm, and Tu (%),
DR = ([93.2 – ta] * [v – 10]0.62) * (0.00004 * v * Tu + 0.066) .
For v < 0.05 m/s (10 fpm), use v = 0.05 m/s (10 fpm).
For DR > 100%, use DR = 100%.
7
TABLE 5.2.4.3
Allowable Vertical Air Temperature Difference
Between Head and Ankles
Vertical Air Temperature Difference °C (°F)
< 3 (< 5.4)
TABLE 5.2.4.4
Allowable Range of the Floor Temperature
Range of Surface Temperature of the Floor °C (°F)
19-29 (66.2-84.2)
Figure 5.2.4.2 Allowable mean air speed as a function of air
temperature and turbulence intensity.
Figure 5.2.4.4
Figure 5.2.4.3 Local thermal discomfort caused by vertical
temperature differences.
The values of DR predicted from this equation must be
within the limits specified for draft in Table 5.2.4. On average,
the turbulence intensity in a large part of the occupied zone of
rooms with mixing ventilation is around 35%, and it is 20% in
rooms with displacement ventilation or without mechanical
ventilation. These values may be used in the above equation
when the turbulence intensity is not measured.
The criteria specified in this section do not apply to the
use of elevated air speed in Section 5.2.3. However, when
occupants choose to turn off the elevated air speed, these criteria apply.
5.2.4.3 Vertical Air Temperature Difference. Thermal
stratification that results in the air temperature at the head
level being warmer than at the ankle level may cause thermal
discomfort. This section specifies allowable differences
between the air temperature at head level and the air temperature at ankle level. Figure 5.2.4.3 gives the predicted percentage of dissatisfied occupants as a function of the air
temperature difference where the head level is warmer than
8
Local discomfort caused by warm and cool
floors.
the ankle level. Thermal stratification in the opposite direction
is rare, is perceived more favorably by occupants, and is not
addressed in this standard.
The allowable differences in air temperature from the
ankle level to the head level may be determined from Table
5.2.4.3. Alternatively, Figure 5.2.4.3 may be used in conjunction with the PD limit for vertical temperature differences in
Table 5.2.4 to determine the allowable differences in air
temperature from the ankle level to the head level.
5.2.4.4 Floor Surface Temperature. Occupants may
feel uncomfortable due to contact with floor surfaces that are
too warm or too cool. The temperature of the floor, rather than
the material of the floor covering, is the most important factor
for foot thermal comfort for people wearing shoes. Figure
5.2.4.4 gives the predicted percentage of dissatisfied occupants as a function of floor temperature. The criteria in this
section are based on people wearing lightweight indoor shoes.
These criteria may also be used for people wearing heavier
footgear, but may be conservative. This standard does not
address the floor temperature required for people not wearing
shoes. Nor does it address acceptable floor temperatures when
people sit on the floor.
The limits for floor temperature are specified in Table
5.2.4.4. Alternatively, Figure 5.2.4.4 may be used in conjunction with the PD limit from Table 5.2.4 to determine the allowable floor temperature range.
ANSI/ASHRAE STANDARD 55-2004
5.2.5 Temperature Variations with Time. Fluctuations
in the air temperature and/or mean radiant temperature may
affect the thermal comfort of occupants. Those fluctuations
under the direct control of the individual occupant do not have
a negative impact on thermal comfort, and the requirements of
this section do not apply to these fluctuations. Fluctuations
that occur due to factors not under the direct control of the
individual occupant (e.g., cycling from thermostatic control)
may have a negative effect on comfort, and the requirements
of this section do apply to these fluctuations. Fluctuations that
occupants experience as a result of moving between locations
with different environmental conditions are allowed as long as
the conditions at all of these locations are within the comfort
zone for these moving occupants.
5.2.5.1 Cyclic Variations. Cyclic variations refer to
those situations where the operative temperature repeatedly
rises and falls, and the period of these variations is not greater
than 15 minutes. If the period of the fluctuation cycle exceeds
15 minutes, the variation is treated as a drift or ramp in operative temperature, and the requirements of Section 5.2.5.2
apply. In some situations, variations with a period not greater
than 15 minutes are superimposed on variations with a longer
period. In these situations, the requirements of Section 5.2.5.1
apply to the component of the variation with a period not
greater than 15 minutes, and the requirements of Section
5.2.5.2 apply to the component of the variation with a period
greater than 15 minutes.
Table 5.2.5.1 specifies the maximum allowable peak-topeak cyclic variation in operative temperature.
5.2.5.2 Drifts or Ramps. Temperature drifts and ramps
are monotonic, noncyclic changes in operative temperature.
The requirements of this section also apply to cyclic variations with a period greater than 15 minutes. Generally, drifts
refer to passive temperature changes of the enclosed space,
and ramps refer to actively controlled temperature changes.
The requirements of this section are the same for drifts and
ramps.
Table 5.2.5.2 specifies the maximum change in operative
temperature allowed during a period of time. For any given
time period, the most restrictive requirements from Table
5.2.5.2 apply. For example, the operative temperature may not
change more than 2.2°C (4.0°F) during a 1.0-h period, and it
also may not change more than 1.1°C (2.0°F) during any 0.25h period within that 1.0-h period. If variations are created as a
result of control or adjustments by the user, higher values may
be acceptable.
5.3 Optional Method for Determining Acceptable
Thermal Conditions in Naturally Conditioned Spaces
For the purposes of this standard, occupant-controlled
naturally conditioned spaces are those spaces where the ther-
mal conditions of the space are regulated primarily by the
occupants through opening and closing of windows. Field
experiments have shown that occupants’ thermal responses in
such spaces depend in part on the outdoor climate and may
differ from thermal responses in buildings with centralized
HVAC systems primarily because of the different thermal
experiences, changes in clothing, availability of control, and
shifts in occupant expectations. This optional method is
intended for such spaces.
In order for this optional method to apply, the space in
question must be equipped with operable windows that open
to the outdoors and that can be readily opened and adjusted by
the occupants of the space. There must be no mechanical cooling system for the space (e.g., refrigerated air conditioning,
radiant cooling, or desiccant cooling). Mechanical ventilation
with unconditioned air may be utilized, but opening and closing of windows must be the primary means of regulating the
thermal conditions in the space. The space may be provided
with a heating system, but this optional method does not apply
when the heating system is in operation. It applies only to
spaces where the occupants are engaged in near sedentary
physical activities, with metabolic rates ranging from 1.0 met
to 1.3 met. See Appendix A for estimation of metabolic rates.
This optional method applies only to spaces where the occupants may freely adapt their clothing to the indoor and/or
outdoor thermal conditions.
Allowable indoor operative temperatures for spaces that
meet these criteria may be determined from Figure 5.3. This
figure includes two sets of operative temperature limits—one
for 80% acceptability and one for 90% acceptability. The 80%
acceptability limits are for typical applications and shall be
used when other information is not available. The 90% acceptability limits may be used when a higher standard of thermal
comfort is desired. Figure 5.3 is based on an adaptive model
of thermal comfort that is derived from a global database of
21,000 measurements taken primarily in office buildings.
The allowable operative temperature limits in Figure 5.3
may not be extrapolated to outdoor temperatures above and
below the end points of the curves in this figure. If the mean
monthly outdoor temperature is less than 10°C (50°F) or greater
than 33.5°C (92.3°F), this option may not be used, and no
specific guidance for naturally conditioned spaces is included in
this standard.
TABLE 5.2.5.1
Allowable Cyclic Operative Temperature Variation
Allowable Peak-to-Peak Variation in
Operative Temperature, °C (°F)
1.1 (2.0)
TABLE 5.2.5.2
Limits on Temperature Drifts and Ramps
Time Period
0.25 h
0.5 h
1h
2h
4h
Maximum Operative Temperature Change Allowed
1.1°C
(2.0°F)
1.7°C
(3.0°F)
2.2°C
(4.0°F)
2.8°C
(5.0°F)
3.3°C
(6.0°F)
ANSI/ASHRAE STANDARD 55-2004
9
Figure 5.3
Acceptable operative temperature ranges for naturally conditioned spaces.
Figure 5.3 accounts for local thermal discomfort effects in
typical buildings, so it is not necessary to address these factors
when using this option. However, if there is reason to believe
that local thermal discomfort is a problem, the criteria in
Section 5.2.4 may be applied.
Figure 5.3 also accounts for people’s clothing adaptation
in naturally conditioned spaces by relating the acceptable
range of indoor temperatures to the outdoor climate, so it is not
necessary to estimate the clothing values for the space.
No humidity or air speed limits are required when this
option is used.
5.4
Description of Thermal Environmental Variables
The following description of the environmental variables
is provided for the purpose of understanding their use in
Section 5. It is not intended to be a measurement specification.
Section 7 specifies measurement requirements. If there is a
discrepancy between the descriptions in this section and the
requirements in Section 7, then the requirements in Section 7
supersede the descriptions in this section for the purpose of
measurement.
For the purposes of Section 5, the thermal environment is
defined with respect to the occupant.
Air temperature is the average temperature of the air
surrounding an occupant. The average is with respect to location and time. As a minimum, the spatial average is the numerical average of the air temperature at the ankle level, the waist
level, and the head level. These levels are 0.1, 0.6, and 1.1 m
(4, 24, and 43 in.), respectively, for seated occupants, and 0.1,
1.1, and 1.7 m (4, 43, and 67 in.) for standing occupants. Intermediate, equally spaced locations may also be included in the
average. When the occupant is located in a directed airflow, the
air temperature on the upstream side shall be used. As a minimum, the temporal average is a three-minute average with at
10
least 18 equally spaced points in time. However, the period
may extend up to 15 minutes to average cyclic fluctuations if
necessary. The temporal average applies to all locations in the
spatial average.
Local air temperature is defined in the same way as the air
temperature except that it refers to a single level (e.g., head
level). At least one location is required at this level. However,
multiple locations around the body may be included to determine a better average.
Mean radiant temperature is defined as the temperature
of a uniform, black enclosure that exchanges the same amount
of thermal radiation with the occupant as the actual enclosure.
It is a single value for the entire body and may be considered
a spatial average of the temperature of surfaces surrounding
the occupant weighted by their view factors with respect to the
occupant. See Chapter 8 in the 2001 ASHRAE Handbook—
Fundamentals3 for a more complete description of mean radiant temperature. For the purposes of Section 5, mean radiant
temperature is also a time-averaged value. As a minimum, the
temporal average is a three-minute average with at least 18
equally spaced points in time. However, the period may extend
up to 15 minutes to average cyclic fluctuations if necessary.
Operative temperature is the average of the air temperature and the mean radiant temperature weighted, respectively,
by the convective heat transfer coefficient and the linearized
radiant heat transfer coefficient for the occupant. See Chapter
8 in the 2001 ASHRAE Handbook—Fundamentals3 for a more
complete description of operative temperature. For occupants
engaged in near sedentary physical activity (with metabolic
rates between 1.0 met and 1.3 met), not in direct sunlight, and
not exposed to air velocities greater than 0.20 m/s (40 fpm), the
relationship can be approximated with acceptable accuracy by
to = (ta + tr) / 2 ,
ANSI/ASHRAE STANDARD 55-2004
where
to = operative temperature,
ta = air temperature, and
tr = mean radiant temperature.
Radiant asymmetry is the difference between the plane
radiant temperature in opposite directions. The plane radiant
temperature is defined similarly to mean radiant temperature
except that it is with respect to a small planar surface element
exposed to the thermal radiation from surfaces from one side
of that plane. The vertical radiant asymmetry is with plane
radiant temperatures in the upward and downward direction.
The horizontal radiant asymmetry is the maximum difference
between opposite plane radiant temperatures for all horizontal
directions. The radiant asymmetry is determined at waist
level—0.6 m (24 in.) for a seated occupant and 1.1 m (43 in.)
for a standing occupant. Time averaging for radiant asymmetry is the same as for mean radiant temperature. See Chapter
8 in the 2001 ASHRAE Handbook—Fundamentals3 for a more
complete description of plane radiant temperature and radiant
asymmetry.
Floor temperature (tf ) is the surface temperature of the
floor when it is in contact with the occupants’ shoes. Since
floor temperatures seldom change rapidly, time averaging
does not need to be considered.
Mean monthly outdoor temperature is the arithmetic
average of the mean daily minimum and mean daily maximum
outdoor (dry-bulb) temperature for the month in question.
Air speed is the average speed of the air to which the body
is exposed. The average is with respect to location and time.
Time averaging and spatial averaging are the same as for air
temperature. However, the time-averaging period extends
only to three minutes. Variations that occur over a period
greater than three minutes shall be treated as multiple different
air speeds.
Turbulence intensity is the ratio of the standard deviation
of the air speed with respect to time and the time-averaged air
speed. The turbulence intensity is primarily for the head/
shoulder portions of the body—the 1.1 m (43 in.) level for
seated occupants and the 1.7 m (67 in.) level for standing occupants. It may also apply to the ankle/lower leg areas if they are
not covered with clothing—the 0.1 m (4 in.) level for both
standing and seated occupants.
Humidity is a general reference to the moisture content of
the air. It may be expressed in terms of several thermodynamic
variables, including vapor pressure, dew-point temperature,
and humidity ratio. It is spatially and temporally averaged in
the same manner as air temperature.
lopes shall be designed so that they are able to maintain the
space at conditions within the range specified in this standard
at all combinations of less extreme conditions that are
expected to occur. The less extreme conditions can include
both internal loads and the external environment. The system
shall have controls that enable it to meet comfort requirements
at less than full system capacity.
The method and design conditions, including the design
exceedance level, appropriate for the intended use of the building shall be selected and should be documented in accordance
with Section 6.1.1.
Design weather data are statistically based and established to explicitly acknowledge certain percentages of
exceedance (e.g., 1% design, 4 month summer basis, 29 hours
of exceedance). This recognizes the impracticality of providing an HVAC system that can meet all loads under all weather
or operating conditions encountered in its lifetime. Thus, in
practice, the requirements of Section 5 may not be met during
excursions from the design conditions. Also, weather-based
exceedance will usually be less than indicated by the exceedance percentage because other design loads will seldom be
concurrent.
Because of differences in metabolic rates between individuals and the resultant differences in response to the environment, actual operating building temperatures cannot be
specified in this standard.
6.1.1 Documentation. Complete plans, descriptions,
component literature, and operation and maintenance instructions for the building systems should be provided and maintained. These should include, but not be limited to, building
system design specifications and design intent as follows.
Note: Some of the sections below may not be applicable to
naturally conditioned buildings.
1.
The design criteria of the system in terms of indoor temperature and humidity, including any tolerance or range, based
on stated design outdoor ambient conditions and total
indoor loads, should be stated. Values assumed for comfort
parameters used in calculation of design temperatures,
including clothing and metabolic rate, should be clearly
stated.
2.
The system input or output capacities necessary to attain the
design indoor conditions at design outdoor ambient conditions should be stated, as well as the full input or output
capacities of the system as supplied and installed.
3.
The limitations of the system to control the environment of
the zone(s) should be stated whether based on temperature,
humidity, ventilation, time of week, time of day, or seasonal
criteria.
4.
The overall space supplied by the system should be shown
in a plan view layout, with all individual zones within it
identified. All registers or terminal units should be shown
and identified with type and flow or radiant value.
5.
Significant structural and decor items should be shown and
identified if they affect indoor comfort. Notes should be
provided to identify which areas within a space and which
locations relative to registers, terminal units, relief grilles,
6. COMPLIANCE
Design
The scope of this standard does not include specific guidance regarding mechanical systems, control systems, or the
thermal envelopes for spaces. Building systems (combinations of mechanical systems, control systems, and thermal
envelopes) shall be designed so that, at design conditions, they
are able to maintain the space at conditions within the range
specified by one of the methods in this standard. Additionally,
the mechanical systems, control systems, and thermal enve6.1
ANSI/ASHRAE STANDARD 55-2004
11
and control sensors should not be obstructed in order to
avoid negatively affecting indoor comfort.
with respect to this standard. Full-scale laboratory testing may
provide a more controlled validation, however.
6.
Areas within any zone that lie outside the comfort control
areas, where people should not be permanently located,
should be identified.
7.
Locations of all occupant adjustable controls should be
identified, and each should be provided with a legend
describing which zone(s) it controls, which function(s) it
controls, how it is to be adjusted, the range of effect it can
have, and the recommended setting for various times of day,
season, or occupancy load.
Measuring Device Criteria
The measuring instrumentation used shall meet the
requirements for measuring range and accuracy given in
ASHRAE Standard 70-19915 or 113-19906 or in ISO 7726,1
and the referenced source shall be so identified.
8.
A block-diagram control schematic should be provided
with sensors, adjustable controls, and actuators accurately
identified for each zone. If zone control systems are independent but identical, one diagram is sufficient if identified
for which zones it applies. If zones are interdependent or
interactive, their control diagram should be shown in total
on one block diagram with the point(s) of interconnection
identified.
9.
The general maintenance, operation, and performance of
the building systems should be stated, followed by more
specific comments on the maintenance and operation of the
automatic controls and manually adjustable controls and
the response of the system to each. Where necessary,
specific seasonal settings of manual controls should be
stated, and major system changeovers that are required to be
performed by a professional service agency should be identified.
10. Specific limits in the adjustment of manual controls should
be stated. Recommendations for seasonal settings on these
controls should be stated, along with the degree of manual
change that should be made at any one time, and the waiting
time between adjustments when trying to fine-tune the
system. A maintenance and inspection schedule for all thermal environmental-related building systems should be
provided.
11. Assumed electrical load for lighting and equipment in
occupied spaces (including diversity considerations) used
in HVAC load calculations should be documented, along
with any other significant thermal and moisture loads
assumed in HVAC load calculations and any other assumptions upon which HVAC and control design is based.
Validation
Validation should be performed as described in Section 7
to demonstrate that the building systems can be operated to
meet the requirements of Section 5 according to the design
intent and under design conditions inclusive of less severe
conditions, as documented in Section 6.1.1.
6.2
7. EVALUATION OF THE THERMAL
ENVIRONMENT
At the design stage, the thermal environment may be evaluated by calculations. Simple hand calculations and computer
models of buildings and systems are available for this purpose.
Use this section to evaluate existing thermal environments
12
7.1
7.2
Measurement Positions
7.2.1 Location of Measurements. Measurements shall
be made in occupied zones of the building at locations where
the occupants are known to or are expected to spend their
time.
Such locations might be workstation or seating areas,
depending on the function of the space. In occupied rooms,
measurements shall be taken at a representative sample of
occupant locations spread throughout the occupied zone. In
unoccupied rooms, the evaluator shall make a good faith estimate of the most significant future occupant locations within
the room and make appropriate measurements.
If occupancy distribution cannot be estimated, then the
measurement locations shall be as follows:
(a) In the center of the room or zone.
(b) 1.0 m (3.3 ft) inward from the center of each of the room's
walls. In the case of exterior walls with windows, the
measurement location shall be 1.0 m (3.3 ft) inward from
the center of the largest window.
In either case, measurements shall be taken in locations
where the most extreme values of the thermal parameters are
estimated or observed to occur. Typical examples might be
near windows, diffuser outlets, corners, and entries. Measurements are to be made sufficiently away from the boundaries of
the occupied zone and from any surfaces to allow for proper
circulation around measurement sensors with positions as
described below.
Absolute humidity need be determined at only one location within the occupied zone in each occupied room or
HVAC-controlled zone, provided it can be demonstrated that
there is no reason to expect large humidity variations within
that space. Otherwise, absolute humidity shall be measured at
all locations defined above.
7.2.2 Height Above Floor of Measurements. Air temperature and air speed shall be measured at the 0.1, 0.6, and
1.1 m (4, 24, and 43 in.) levels for sedentary occupants at the
locations specified in Section 7.2.1. Standing activity measurements shall be made at the 0.1, 1.1, and 1.7 m (4, 43, and
67 in.) levels. Operative temperature or PMV-PPD shall be
measured or calculated at the 0.6 m (24 in.) level for seated
occupants and the 1.1 m (43 in.) level for standing occupants.
Radiant asymmetry shall be measured at the 0.6 m (24 in.)
level for seated occupants and the 1.1 m (43 in.) for standing
occupants. If desk-level furniture (that is in place) blocks the
view of strong radiant sources and sinks, the measurements are
to be taken above desktop level. Floor surface temperatures are
to be measured with the anticipated floor coverings installed.
Humidity shall be measured at any level within the occupied
zone if only one measurement location is required. Otherwise
ANSI/ASHRAE STANDARD 55-2004
it shall be measured at the 0.6 m (24 in.) level for seated occupants and the 1.1 m (43 in.) level for standing occupants.
7.3
Measurement Periods
7.3.1 Air Speed. The measuring period for determining
the average air speed at any location shall be three minutes.
Turbulence intensity is measured in the same period by calculating the ratio of the standard deviation for the period to the
average air speed. (See Section 3 for the definition of response
time and its relation to the time constant.)
7.3.2 Temperature Cycles and Drifts. For determining
compliance with the non-steady-state requirements of Section
5, the rate of change of operative temperature is used. It is the
difference between maximum and minimum operative temperatures measured during the same cycle, divided by the
elapsed time in minutes.
Rate of change (degrees/h)
= 60 (to, max – to, min) / time (minutes)
The measurements shall be made every five minutes or
less for at least two hours to establish the nature of the temperature cycle. The use of an automatic recorder is the preferred
method of measurement; however, it is possible to make the
measurements required in this section without the use of
recording equipment.
7.3.3 Clothing and Activity. In buildings, it may be
appropriate to measure the clothing and activity levels of the
occupants. These shall be estimated in the form of mean values over a period of 0.5 to 1.0 hour immediately prior to measuring the thermal parameters.
Measuring Conditions
In order to determine the effectiveness of the building
system at providing the environmental conditions specified in
this standard, measurements shall be made under the following conditions.
To test during the heating period (winter conditions), the
measurements required shall be made when the indooroutdoor temperature difference is not less than 50% of the
difference used for design and with cloudy to partly cloudy sky
conditions. If these sky conditions are rare and not representative of the sky conditions used for design, then sky conditions representative of design conditions are acceptable.
To test during the cooling period (summer conditions),
the measurements required shall be made when the outdoorindoor temperature difference and humidity difference are not
less than 50% of the differences used for design and with clear
to partly cloudy sky conditions. If these sky conditions are rare
and not representative of the sky conditions used for design,
then sky conditions representative of design conditions are
acceptable.
To test interior zones of large buildings, the measurements required shall be made with the zone loaded to at least
50% of the design load for at least one complete cycle of the
HVAC system, if the system is not proportionally controlled.
Simulation of heat generated by occupants is recommended.
7.4
ANSI/ASHRAE STANDARD 55-2004
Mechanical Equipment Operating Conditions
In order to determine appropriate corrective actions
following the use of this standard to analyze the environment,
the following operations of the mechanical system shall be
measured concurrently with the environmental data:
7.5
•
•
•
•
•
•
•
•
•
Air supply rate into the space being measured
Room/supply air temperature differential
Type and location of room diffuser or air outlet
Discharge air speed
Perimeter heat type, location, and status
Return grille location and size
Type of air supply system
Surface temperatures of heated or cooled surfaces
Water supply and return temperatures of hydronic systems
7.6 Validating the Thermal Environment for
New Buildings and Installations
7.6.1 Define Criteria. Before validating a thermal environment that meets the requirements of this standard, the original design conditions specified shall be defined. From this
definition, the validation team will evaluate the system’s ability to meet and maintain the desired comfort level(s). The
comfort criteria definition shall include, but not be limited to,
the following:
•
•
•
Temperature (air, radiant, surface)
Humidity
Air speed
The environmental conditions that were originally specified shall be defined as well to ensure that measurements
taken correspond correctly to the design parameters. Environmental conditions shall include, but again are not limited to,
the following:
•
•
•
•
Outdoor temperature design conditions
Outdoor humidity design conditions
Clothing (seasonal)
Activity expected
7.6.2 Select Validation Method. In order to determine
the thermal environment’s ability to meet the defined criteria
as outlined in Section 7.6.1 above, there are two methods (one
described in Section 7.6.2.1 and the other in Section 7.6.2.2)
that can be implemented. The first method of validating the
thermal environment is to statistically determine occupant
satisfaction through the evaluation of survey results. The second is to technically establish comfort conditions through the
analysis of environment variables.
7.6.2.1 Survey Occupants. The purpose of this standard is to ensure that a room, building, etc., is comfortable for
a substantial majority (at least 80%) of the occupants. Therefore, an effective way to evaluate the environmental conditions is to survey the occupants. This survey should be
performed for every operating mode, in every design condition. This would require a survey check sheet to be provided
by the team responsible for validating the thermal environment of the space. The sheet shall have, as a minimum, the following data for the occupant to fill in:
13
•
•
•
•
•
•
•
•
•
Occupant’s name, date, and time
Approximate outside air temperature
Clear sky/overcast (if applicable)
Seasonal conditions
Occupant’s clothing
Occupant’s activity level
Applicable equipment
General thermal comfort level
Occupant’s location
In addition to the occupant’s data, space shall be provided
for the surveyor to number the survey, summarize the results,
and sign his/her name. A sample check sheet and clothing
table are provided in Appendix E.
7.6.2.2 Analyze Environment Variables. The second
method for evaluating the comfort conditions is to analyze
specific environmental data for compliance with the requirements of this standard. Each application of validating the thermal environment is unique. A specific test plan will be
required to accommodate the project scope.
Assess the environment for which comfort conditions are
going to be verified. Determine the need to verify floor surface
temperature, vertical temperature difference, and radiant
temperature asymmetry. When this need exists, it is important
to ensure the maximum potential for variance is exploited
(e.g., take radiant asymmetry temperature reading on a sunny
day with the blinds open).
Under all expected operating conditions, air speed (nondirectional), air temperature, and humidity shall be verified.
•
•
Verify satisfactory air speed with a group of readings
taken at a strategic location within the space. For VAV
systems, readings shall be taken at maximum flow with
minimum supply air temperature.
Determine the best location for providing accurate air
temperature and humidity readings. Proof of performance for both air temperature and humidity shall
require trended data.
Where variables are going to be trended, successful
comfort control shall be a function of steady-state performance. Steady state shall require that the trended variable
14
remain within a specified range without cycling. Cycling is
defined as fluctuation over 50% of the permitted range every
15 minutes or more frequently. This verification shall include
trending variables for at least one occupied cycle during each
seasonal condition. When thermal conditions in the occupied
zone have a high sensitivity to time of day and weather conditions, the measurement shall be made such that the high and
low extremes of the thermal parameters are determined.
ASHRAE Standard 113-19906 offers a procedure for determining air speed and temperature variations in building spaces
and provides additional guidance for the measurement of
mechanical equipment parameters.
7.6.3 Provide Documentation. The effort of validation
also involves ensuring a thoroughly documented process.
Whichever method of validating the thermal environment is
chosen, the process shall be well documented.
7.6.3.1 Documenting Surveys. When the occupants of
a building are surveyed as outlined in Section 7.6.2.1, the survey method shall be developed, written, and turned over, with
the sample survey sheets, to the appropriate parties for review
and approval.
7.6.3.2 Documenting Variable Analysis. For analysis
of the environmental variables outlined in Section 7.6.2, the
trend logs and data analysis shall be prepared. Again, the
method of trending must be included with this submission, if
it has not been provided prior to validation, for approval.
8. REFERENCES
1. ISO 7726:1998, Ergonomics of the thermal environment-Instruments for measuring physical quantities.
2. ISO 7730:1994, Moderate thermal environments--Determination of the PMV and PPD indices and specification
of the conditions for thermal comfort.
3. 2001 ASHRAE Handbook—Fundamentals.
4. ASHRAE Thermal Comfort Tool CD (ASHRAE Item
Code 94030).
5. ASHRAE Standard 70-1991, Method of Testing for Rating
the Performance of Air Outlets and Inlets.
6. ASHRAE Standard 113-1990, Method of Testing for Room
Air Diffusion.
ANSI/ASHRAE STANDARD 55-2004
(This is a normative appendix and is part of this standard.)
NORMATIVE APPENDIX A—ACTIVITY LEVELS
Metabolic Rates for Typical Tasks
Metabolic Rate
Met Units
W/m2
(Btu/h⋅ft2)
Sleeping
0.7
40
(13)
Reclining
0.8
45
(15)
Seated, quiet
1.0
60
(18)
Standing, relaxed
1.2
70
(22)
0.9 m/s, 3.2 km/h, 2.0 mph
2.0
115
(37)
1.2 m/s, 4.3 km/h, 2.7 mph
2.6
150
(48)
1.8 m/s, 6.8 km/h, 4.2 mph
3.8
220
(70)
Seated, reading, or writing
1.0
60
(18)
Typing
1.1
65
(20)
Filing, seated
1.2
70
(22)
Filing, standing
1.4
80
(26)
Walking about
1.7
100
(31)
Lifting/packing
2.1
120
(39)
1.0-2.0
60-115
(18-37)
Activity
Resting
Walking (on level surface)
Office Activities
Driving/Flying
Automobile
Aircraft, routine
1.2
70
(22)
Aircraft, instrument landing
1.8
105
(33)
Aircraft, combat
2.4
140
(44)
Heavy vehicle
3.2
185
(59)
Cooking
1.6-2.0
95-115
(29-37)
House cleaning
2.0-3.4
115-200
(37-63)
2.2
130
(41)
Miscellaneous Occupational Activities
Seated, heavy limb movement
Machine work
sawing (table saw)
light (electrical industry)
heavy
Handling 50 kg (100 lb) bags
Pick and shovel work
1.8
105
(33)
2.0-2.4
115-140
(37-44)
4.0
235
(74)
4.0
235
(74)
4.0-4.8
235-280
(74-88)
2.4-4.4
140-255
(44-81)
Miscellaneous Leisure Activities
Dancing, social
Calisthenics/exercise
3.0-4.0
175-235
(55-74)
Tennis, single
3.6-4.0
210-270
(66-74)
Basketball
5.0-7.6
290-440
(92-140)
Wrestling, competitive
7.0-8.7
410-505
(129-160)
ANSI/ASHRAE STANDARD 55-2004
15
Use of Metabolic Rate Data
These data are reproduced from Chapter 8 of the 2001
ASHRAE Handbook—Fundamentals. The values in the table
represent typical metabolic rates per unit of skin surface area
for an average adult (DuBois area = 1.8 m2, or 19.6 ft2) for
activities performed continuously. This handbook chapter
provides additional information for estimating and measuring
activity levels. General guidelines for the use of these data
follow.
Every activity that may be of interest is not included in
this table. Users of this standard should use their judgment to
match the activities being considered to comparable activities
in the table. Some of the data in this table are reported as a
range, and some as a single value. The format for a given entry
is based on the original data source and is not an indication of
when a range of values should or should not be utilized. For all
activities except sedentary activities, the metabolic rate for a
given activity is likely to have a substantial range of variation
that depends on the individual performing the task and the
circumstances under which the task is performed.
A time-weighted average metabolic rate may be used for
individuals with activities that vary over a period of one hour
or less. For example, a person who typically spends 30 minutes
out of each hour “lifting/packing,” 15 minutes “filing, standing,” and 15 minutes “walking about” has an average metabolic rate of 0.50 × 2.1 + 0.25 × 1.4 + 0.25 × 1.7 = 1.8 met. Such
averaging should not be applied when the period of variation
is greater than one hour. For example, a person who is engaged
in “lifting/packing” for one hour and then “filing, standing”
the next hour should be treated as having two distinct metabolic rates.
As metabolic rates increase above 1.0 met, the evaporation of sweat becomes an increasingly important factor for
thermal comfort. The PMV method does not fully account for
this factor, and this standard should not be applied to situations
where the time-averaged metabolic rate is above 2.0 met. Typically, rest breaks (scheduled or hidden) or other operational
factors (get parts, move products, etc.) combine to limit timeweighted metabolic rates to about 2.0 met in most applications.
Time averaging of metabolic rates only applies to an individual. The metabolic rates associated with the activities of
various individuals in a space may not be averaged to find a
single, average metabolic rate to be applied to that space. The
range of activities of different individuals in the space, and the
environmental conditions required for those activities, should
be considered in applying this standard. For example, the
customers in a restaurant may have a metabolic rate near 1.0
met, while the servers may have metabolic rate closer to 2.0
met. Each of these groups of occupants should be considered
separately in determining the conditions required for comfort.
In some situations, it will not be possible to provide an acceptable level or the same level of comfort to all disparate groups
of occupants (e.g., restaurant customers and servers).
The metabolic rates in this table were determined when
the subjects’ thermal sensation was close to neutral. It is not
yet known the extent to which people may modify their metabolic rate to decrease warm discomfort.
16
(This is a normative appendix and is part of this standard.)
NORMATIVE APPENDIX B—
CLOTHING INSULATION
The amount of thermal insulation worn by a person has a
substantial impact on thermal comfort and is an important
variable in applying this standard. Clothing insulation is
expressed in a number of ways. In this standard, the clothing
insulation of an ensemble expressed as a clo-value (Icl) is used.
Users not familiar with clothing insulation terminology are
referred to Chapter 8, 2001 ASHRAE Handbook—Fundamentals, for more information.
The insulation provided by clothing can be determined by
a variety of means and, if accurate data are available from
other sources, such as measurement with thermal manikins,
these data may be used. When such information is not available, the tables in this appendix may be used to estimate clothing insulation using one of the methods described below.
Regardless of the source of the clothing insulation value, this
standard shall not be used with clothing ensembles with more
than 1.5 clo of insulation. Also, this standard should not be
used with clothing that is highly impermeable to moisture
transport (e.g., chemical protective clothing or rain gear).
Three methods for estimating clothing insulation are
presented. The methods are listed in order of accuracy and
should be used in this order of preference.
•
•
•
Method 1: Table B1 lists the insulation provided by a
variety of common clothing ensembles. If the ensemble
in question matches reasonably well with one of the
ensembles in this table, then the indicated value of Icl
should be used.
Method 2: Table B2 presents the thermal insulation of a
variety of individual garments. These garments may be
added to or subtracted from the ensembles in Table B1
to estimate the insulation of ensembles that differ in garment composition from those in Table B1. For example,
if long underwear bottoms are added to Ensemble 5 in
Table B1, the insulation of the resulting ensemble is
estimated as Icl = 1.01 clo + 0.15 clo = 1.16 clo.
Method 3: A complete clothing ensemble may be
defined using a combination of the garments listed in
Table B2. The insulation of the ensemble is estimated as
the sum of the individual values listed in Table B2. For
example, the estimated insulation of an ensemble consisting of overalls worn with a flannel shirt, T-shirt,
briefs, boots, and calf-length socks is Icl = 0.30 + 0.34 +
0.08 + 0.04 + 0.10 + 0.03 = 0.89 clo.
Tables B1 and B2 are for a standing person. A sitting
posture results in a decreased thermal insulation due to
compression of air layers in the clothing. This decrease may be
offset by insulation provided by the chair. Table B3 shows the
net effect on clothing insulation for typical indoor clothing
ensembles that results from sitting in a chair. These data may
be used to adjust clothing insulation calculated using any of
the above methods. For example, the clothing insulation for a
person wearing Ensemble 3 from Table B1 and sitting in an
ANSI/ASHRAE STANDARD 55-2004
executive chair is 0.96 clo + 0.15 clo = 1.11 clo. For many
chairs, the net effect of sitting is a minimal change in clothing
insulation. For this reason, it is recommended that no adjustment be made to clothing insulation if there is uncertainty as
to the type of chair and/or if the activity for an individual
includes both sitting and standing.
where M is the metabolic rate in met units and Icl is the insulation without activity. For metabolic rates less than or equal
to 1.2 met, no adjustment is recommended.
Clothing variability among occupants in a space is an
important consideration in applying this standard. This variability takes two forms. In the first form, different individuals
wear different clothing due to factors unrelated to the thermal
conditions. Examples include different clothing style preferences for men and women and offices where managers are
expected to wear suits while other staff members may work in
shirtsleeves. In the second form, the variability results from
adaptation to individual differences in response to the thermal
environment. For example, some individuals may wear sweaters, while others wear short-sleeve shirts in the same environment if there are no constraints limiting what is worn. The first
form of variability may result in differences in the requirements for thermal comfort between the different occupants,
and these differences should be addressed in applying this
standard. In this situation, it is not acceptable to determine the
average clothing insulation of various groups of occupants to
determine the thermal environmental conditions needed for all
occupants. Each group must be considered separately. Where
the variability within a group of occupants is of the second
form and is a result only of individuals freely making adjustments in clothing to suit their individual thermal preferences,
it is acceptable to use a single representative average clothing
insulation value for everyone in that group.
When a person is sleeping or resting in a reclining
posture, the bed and bedding may provide considerable thermal insulation. It is not possible to determine the thermal insulation for most sleeping or resting situations unless the
individual is immobile. Individuals will adjust the bedding to
suit individual preferences. Provided adequate bedding materials are available, the thermal environmental conditions
desired for sleeping and resting vary considerably from person
to person and cannot be determined by the methods included
in this standard.
For near sedentary activities where the metabolic rate is
approximately 1.2 met, the effect of changing clothing insulation on the optimum operative temperature is approximately
6°C (11°F) per clo. For example, Table B2 indicates that
adding a thin, long-sleeve sweater to a clothing ensemble
increases clothing insulation by approximately 0.25 clo.
Adding this insulation would lower the optimum operative
temperature by approximately 6°C/clo × 0.25 clo = 1.5°C
(11°F/clo × 0.25 clo = 2.8°F). The effect is greater with higher
metabolic rates.
Tables B1 and B2 are for a person that is not moving.
Body motion decreases the insulation of a clothing ensemble
by pumping air through clothing openings and/or causing air
motion within the clothing. This effect varies considerably
depending on the nature of the motion (e.g., walking versus
lifting) and the nature of the clothing (stretchable and snug
fitting versus stiff and loose fitting). Because of this variability, accurate estimates of clothing insulation for an active
person are not available unless measurements are made for the
specific clothing under the conditions in question (e.g., with a
walking manikin). A rough estimate of the clothing insulation
for an active person is
Icl, active = Icl × (0.6 + 0.4 / M)
ANSI/ASHRAE STANDARD 55-2004
1.2 met < M < 2.0 met
17
TABLE B1
Clothing Insulation Values for Typical Ensemblesa
Icl
(clo)
Garments Includedb
Clothing Description
1) Trousers, short-sleeve shirt
0.57
2) Trousers, long-sleeve shirt
0.61
3) #2 plus suit jacket
0.96
4) #2 plus suit jacket, vest, T-shirt
1.14
5) #2 plus long-sleeve sweater, T-shirt
1.01
6) #5 plus suit jacket, long underwear bottoms
1.30
7) Knee-length skirt, short-sleeve shirt (sandals)
0.54
8) Knee-length skirt, long-sleeve shirt, full slip
0.67
9) Knee-length skirt, long-sleeve shirt, half slip, long-sleeve sweater
1.10
10) Knee-length skirt, long-sleeve shirt, half slip, suit jacket
1.04
11) Ankle-length skirt, long-sleeve shirt, suit jacket
1.10
Shorts
12) Walking shorts, short-sleeve shirt
0.36
Overalls/Coveralls
13) Long-sleeve coveralls, T-shirt
0.72
14) Overalls, long-sleeve shirt, T-shirt
0.89
15) Insulated coveralls, long-sleeve thermal underwear tops and bottoms
1.37
Athletic
16) Sweat pants, long-sleeve sweatshirt
0.74
Sleepwear
17) Long-sleeve pajama tops, long pajama trousers, short 3/4 length robe (slippers, no socks)
0.96
Trousers
Skirts/Dresses
a
b
Data are from Chapter 8 in the 2001 ASHRAE Handbook—Fundamentals.
All clothing ensembles, except where otherwise indicated in parentheses, include shoes, socks, and briefs or panties. All skirt/dress clothing ensembles include
pantyhose and no additional socks.
18
ANSI/ASHRAE STANDARD 55-2004
TABLE B2
Garment Insulationa
Garment Descriptionb
Iclu (clo)
Dress and Skirtsc
Underwear
Bra
0.01
Skirt (thin)
0.14
Panties
0.03
Skirt (thick)
0.23
Men's briefs
0.04
Sleeveless, scoop neck (thin)
0.23
T-shirt
0.08
Sleeveless, scoop neck (thick), i.e.,
jumper
0.27
Half-slip
0.14
Short-sleeve shirtdress (thin)
0.29
Long underwear bottoms
0.15
Long-sleeve shirtdress (thin)
0.33
Full slip
0.16
Long-sleeve shirtdress (thick)
0.47
Long underwear top
0.20
Sweaters
Footwear
Sleeveless vest (thin)
0.13
Ankle-length athletic
socks
0.02
Sleeveless vest (thick)
0.22
Pantyhose/stockings
0.02
Long-sleeve (thin)
0.25
Sandals/thongs
0.02
Long-sleeve (thick)
0.36
Shoes
0.02
Suit Jackets and Vestsd
Slippers (quilted, pile
lined)
0.03
Sleeveless vest (thin)
0.10
Calf-length socks
0.03
Sleeveless vest (thick)
0.17
Knee socks (thick)
0.06
Single-breasted (thin)
0.36
Boots
0.10
Single-breasted (thick)
0.42
Double-breasted (thin)
0.44
Double-breasted (thick)
0.48
Shirts and Blouses
Sleeveless/scoop-neck
blouse
0.13
Short-sleeve knit sport
shirt
0.17
Short-sleeve dress shirt
0.19
Sleeveless short gown (thin)
0.18
Long-sleeve dress shirt
0.25
Sleeveless long gown (thin)
0.20
Long-sleeve flannel shirt
0.34
Short-sleeve hospital gown
0.31
Long-sleeve sweatshirt
0.34
Short-sleeve short robe (thin)
0.34
Short-sleeve pajamas (thin)
0.42
Trousers and Coveralls
a
b
c
d
Garment Descriptionb
Iclu (clo)
Sleepwear and Robes
Short shorts
0.06
Long-sleeve long gown (thick)
0.46
Walking shorts
0.08
Long-sleeve short wrap robe (thick)
0.48
Straight trousers (thin)
0.15
Long-sleeve pajamas (thick)
0.57
Straight trousers (thick)
0.24
Long-sleeve long wrap robe (thick)
0.69
Sweatpants
0.28
Overalls
0.30
Coveralls
0.49
Data are from Chapter 8 in the 2001 ASHRAE Handbook—Fundamentals.
“Thin” refers to garments made of lightweight, thin fabrics often worn in the summer; “thick” refers to garments made of heavyweight, thick fabrics often worn in the winter.
Knee-length dresses and skirts.
Lined vests.
ANSI/ASHRAE STANDARD 55-2004
19
TABLE B3
Typical Added Insulation when Sitting on a Chair
(Valid for Clothing Ensembles with Standing Insulation Values of 0.5 clo < Icl < 1.2 clo)
Net chaira
0.00 clo
Metal chair
0.00 clo
Wooden side arm chairb
0.00 clo
Wooden stool
+0.01 clo
Standard office chair
+0.10 clo
Executive chair
+0.15 clo
a A chair constructed from thin, widely spaced cords that provide no thermal insulation. Included for comparison purposes only.
b Chair used in most of the basic studies of thermal comfort that were used to establish the PMV-PPD index.
(This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for
conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may
contain material that has not been subject to public review or a consensus process.)
INFORMATIVE APPENDIX C—
ACCEPTABLE APPROXIMATION FOR
OPERATIVE TEMPERATURE
The assumption that operative temperature equals air temperature is acceptable when these four conditions exist:
1.
There is no radiant and/or radiant panel heating or radiant panel cooling system;
2.
The average U-factor of the outside window/wall is determined by the following equation:
50
U W < --------------------t d,i – t d,e
(SI)
15.8
U W < --------------------t d,i – t d,e
(IP)
where
Uw = average U-factor of window/wall, W/m2·K (Btu/h⋅ft2⋅°F)
td,i = internal design temperature, °C (°F)
td,e = external design temperature, °C (°F);
3.
Window solar heat gain coefficients (SHGC) are less than 0.48; and
4.
There is no major heat generating equipment in the space.
Calculation of the Operative Temperature Based on Air and Mean-Radiant Temperature
In most practical cases where the relative air speed is small (< 0.2 m/s, 40 fpm) or where the difference between mean radiant
and air temperature is small (< 4°C, 7°F), the operative temperature can be calculated with sufficient approximation as the mean
value of air temperature and mean radiant temperature.
For higher precision and other environments, the following formula may be used:
top = A ta + (1 - A) tr
where
top = operative temperature,
ta = air temperature,
tr = mean radiant temperature, and
the value of A can be found from the values below as a function of the relative air speed, vr.
vr
< 0.2 m/s
(<40 fpm)
0.2 to 0.6 m/s
(40 to 120 fpm)
0.6 to 1.0 m/s
(120 to 200 m/s)
A
0.5
0.6
0.7
20
ANSI/ASHRAE STANDARD 55-2004
(This is a normative appendix and is part of this standard.)
NORMATIVE APPENDIX D—COMPUTER PROGRAM FOR CALCULATION OF PMV-PPD
(Reference: Annex D of ISO 7730. Used with permission from ISO. For additional technical information and an I-P version of
the equations in this appendix, refer to item 6 in References, Section 8, the ASHRAE Thermal Comfort Tool CD. The ASHRAE
Thermal Comfort Tool allows for IP inputs and outputs, but the algorithm is implemented in SI.)
ANSI/ASHRAE STANDARD 55-2004
21
EXAMPLE—Values used to generate the comfort envelope in Figure 5.2.1.1.
22
Run
Air Temp.
RH
Radiant Temp.
#
°F
%
°F
1
67.3
19.6
86
67.3
19.6
20
0.10
2
75.0
23.9
66
75.0
23.9
20
0.10
3
78.2
25.7
15
78.2
25.7
20
0.10
1.1
4
70.2
21.2
20
70.2
21.2
20
0.10
5
74.5
23.6
67
74.5
23.6
20
0.10
6
80.2
26.8
56
80.2
26.8
20
7
82.2
27.9
13
82.2
27.9
8
76.5
24.7
16
76.5
24.7
C
C
Air Speed
FPM
m/s
Met.
PPD
%
CLO
PMV
1.1
1
-0.5
10
1.1
1
0.5
10
1
0.5
10
1.1
1
-0.5
10
1.1
0.5
-0.5
10
0.10
1.1
0.5
0.5
10
20
0.10
1.1
0.5
0.5
10
20
0.10
1.1
0.5
-0.5
10
ANSI/ASHRAE STANDARD 55-2004
(This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for
conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may
contain material that has not been subject to public review or a consensus process.)
INFORMATIVE APPENDIX E—
THERMAL ENVIRONMENT SURVEY
THERMAL ENVIRONMENT SURVEY
Survey Number:
WHITE SECTIONS TO BE FILLED IN BY OCCUPANT
Surveyor’s Name:
1. Occupant’s Name:
11. Occupant Location in Area
(Place an “X” in the approximate place where you most
often work.)
2. Date:
3. Time:
4. Approx. Outside Air Temperature (°F or °C):
5. Sky:
❑ Clear
❑ Mixed (Sun & Clouds)
6. Seasonal Conditions
❑ Winter ❑ Spring ❑ Summer
❑ Overcast
❑ Fall
7. Occupant’s Clothing
SURVEYOR’S USE ONLY
Please refer to the attached Table 1. Place a check mark next to the articles of clothing that you are
currently wearing as you fill out this sheet. If you are wearing articles of clothing not listed in the Clothing Insulation Summary:
table, please enter them into the space provided below.
Article:
Total Icl = ____________ clo
Article:
8. Occupant Activity Level (Check the one that is most appropriate)
1. ❑ Reclining
2. ❑ Seated Quite
3. ❑ Office, school
4. ❑ Standing Relaxed
5. ❑ Light Activity Standing
6. ❑ Medium Activity, Standing
7. ❑ High Activity
Metabolic Rates (met)
1. 0.8 met
2. 1.0 met
3. 1.2 met
4. 1.2 met
5. 1.6 met
6. 2.0 met
7. 3.0 met
9. Equipment (Equipment adding or taking away from the heat load.)
Item (computers, copiers, lighting, fans, etc.)
Quantity
Total Heat Added/ Subtracted
10. General Thermal Comfort (Check the one that is most appropriate)
1. ❑ Hot
2. ❑ Warm
3. ❑ Slightly Warm
4. ❑ Neutral
5. ❑ Slightly Cool
6. ❑ Cool
7. ❑ Cold
Thermal Sensation Scale
1. + 3
2. + 2
3. + 1
4. 0
5. – 1
6. – 2
7. – 3
General Environment Comments:
Area Summary:
Room/Building Type:
Outside Relative Humidity:
%
Thermostat Setting:
o
F or oC
Humidity setpoint:
%
Total Number of Occupants:
ANSI/ASHRAE STANDARD 55-2004
23
TABLE 1
Clothing Ensembles
Description
Trousers, short-sleeve shirt
Trousers, long-sleeve shirt
Trousers, long-sleeve shirt plus suit jacket
Trousers, long-sleeve shirt plus suit jacket, vest, T-shirt
Trousers, long-sleeve shirt plus long sleeve sweater, T-shirt
Trousers, long-sleeve shirt plus long sleeve sweater, T-shirt plus suit jacket, long underwear bottoms
Knee-length skirt, short-sleeve shirt (sandals)
Knee-length skirt, long-sleeve shirt, full slip
Knee-length skirt, long-sleeve shirt, half slip, long-sleeve sweater
Ankle-length skirt, long-sleeve shirt, suit jacket
Walking shorts, short-sleeve shirt
Long-sleeve coveralls, T-shirt
Overalls, long-sleeve shirt, T-shirt
Insulated coveralls, long-sleeve thermal underwear tops and bottoms
Athletic sweat pants, long-sleeve sweatshirt
24
ANSI/ASHRAE STANDARD 55-2004
(This appendix is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject
to public review or a consensus process.)
INFORMATIVE APPENDIX F—BIBLIOGRAPHY
ASHRAE Standard 70-1991, Method of Testing for Rating
the Performance of Air Outlets and Inlets.
ASHRAE Standard 113-1990, Method of Testing for Room
Air Diffusion.
ASHRAE Handbook—2001 Fundamentals.
Berglund, L.G. 1979. Thermal acceptability. ASHRAE
Transactions 85(2):825-834.
Berglund, L.G., and R.R. Gonzalez. 1978. Application of
acceptable temperature drifts to built environments as a
mode of energy conservation. ASHRAE Transactions
84(1):110-121.
Berglund, L.G., and R.R. Gonzalez. 1978. Occupant acceptability of eight-hour-long temperature ramps in the summer at low and high humidities. ASHRAE Transactions
84(2):278-284.
Berglund, L.G., and A.P. Gagge. 1979. Thermal comfort and
radiant heat. Proceedings of the 3rd National Passive
Solar Conference of The American Section of The International Solar Energy Society, Inc.
Berglund, L.G., and A.P.R. Fobelets. 1987. Subjective
human response to low-level air currents and asymmetric radiation. ASHRAE Transactions 93(1):497-523.
Bligh, J., and K.G. Johnson. 1973. Glossary of terms for
thermal physiology. J. Appl. Physiol. 35941-961.
Breunis, K., and J.P. deGroot. 1987. Relative humidity of the
air and ocular discomfort in a group of susceptible office
workers. Proceedings of the Fourth International Conference on Indoor Air Quality and Climate 2:625-629.
de Dear, R.J., and G.S. Brager. 1998. Developing an adaptive
model of thermal comfort and preference. ASHRAE
Transactions 104(1a):145-167.
de Dear, R.J., and M.E. Fountain. 1994. Field experiments
on occupant comfort and office thermal environments in
a hot-humid climate. ASHRAE Transactions
100(2):457-475.
Donnini, G., J. Molina, C. Martello, D.H.C. Lai, L.H. Kit,
C.Y. Chang, M. Laflamme, V.H. Nguyen, and F.
Haghighat. 1996. Field study of occupant comfort and
office thermal environment in a cold climate, Final
Report, ASHRAE RP-821.
Fanger, P.O. 1982. Thermal Comfort. Robert E. Krieger,
Malabar, FL.
Fanger, P.O., B.M. Ipsen, G. Langkilde, B.W. Olesen, N.K.
Christensen, and S. Tanabe. 1985. Comfort limits for
asymmetric thermal radiation. Energy and Buildings
8:225-236.
Fanger, P.O., B.W. Olesen, G. Langkilde, and L. Banhidi.
1980. Comfort limits for heated ceilings. ASHRAE
Transactions 86(2):141-156.
ANSI/ASHRAE STANDARD 55-2004
Fanger, P.O., A. K. Melikov, H. Hanzawa, and J. Ring. 1988.
Air turbulence and sensation of draught. Energy and
Buildings 12:21-39.
Fanger, P.O., and N.K. Christensen. 1986. Perception of
draught in ventilated spaces. Ergonomics 29:215-235.
Fishman, D.S., and S.L. Pimbert. 1979. Survey of subjective
responses to the thermal environment in offices. Indoor
Climate, P.O. Fanger and O. Valbjorn (eds.), Danish
Building Research Institute, Copenhagen.
Fobelets, A.P.R., and A.P. Gagge. 1988. Rationalization of
the effective temperature, ET, as a measure of the
enthalpy of the human indoor environment. ASHRAE
Transactions 94(1):12-31.
Fountain, M., et al. 1996. An investigation of thermal comfort at high humidities, Final Report of Research Project
RP-860, ASHRAE.
Gagge, A.P., and R.G. Nevins. 1976. Effect of energy conservation guidelines on comfort, acceptability and
health, Final Report of Contract #CO-04-51891-00,
Federal Energy Administration.
Gagge, A.P., Y. Nishi, and R.G. Nevins. 1976. The role of
clothing in meeting FEA energy conservation guidelines. ASHRAE Transactions 82(2):234-247.
Griffiths, I.D., and D.A. McIntyre. 1974. Sensitivity to temporal variations in thermal conditions. Ergonomics
17:499-507.
Goldman, R.F. 1978. The role of clothing in achieving
acceptability of environmental temperatures between
65°F and 85°F (18°C and 30°C). Energy Conservation
Strategies in Buildings, J.A.J. Stolwijk, (Ed.) Yale University Press, New Haven.
Hanzawa, H., A.K. Melikov, and P.O. Fanger. 1987. Airflow
characteristics in the occupied zone of ventilated spaces.
ASHRAE Transactions 93(1):524-539.
ISO 7726:1998, Ergonomics of the Thermal Environment—
Instruments for Measuring Physical Quantities.
ISO 7730:1994, Moderate Thermal Environments—Determination of the PMV and PPD Indices and Specification
of the Conditions for Thermal Comfort.
Jones, B.W., K. Hsieh, and M. Hashinaga. 1986. The effect
of air velocity on thermal comfort at moderate activity
levels. ASHRAE Transactions 92(2b):761-769.
Knudsen, H.N., R.J. de Dear, J.W. Ring, T.L. Li, T.W. Puentener, and P.O. Fanger. 1989. Thermal comfort in passive
solar buildings, Final Report to the Commission of the
European Communities, Directorate-General for Science, Research and Development. Research Project
EN3S-0035-DK(B). (Lyngby Copenhagen: Technical
University of Denmark).
Laviana, J.E., F.H. Rohles, and P.E. Bullock. 1988. Humidity, comfort and contact lenses. ASHRAE Transactions
94(1):3-11.
Lammers, J.T.H., L.G. Berglund, and J.A.J. Stolwijk. 1978.
Energy conservation and thermal comfort in a New York
City high rise office building. Environmental Management 2:113-117.
McCullough, E.A., and D.P. Wyon. 1983. Insulation characteristics of winter and summer indoor clothing.
ASHRAE Transactions 89(2b):614-633.
25
McCullough, E.A., B.W. Jones, and J. Huck. 1985. A comprehensive data base for estimating clothing insulation.
ASHRAE Transactions 91(2a):29-47.
McCullough, E.A., B.W. Olesen, and S. Hong. 1994. Thermal insulation provided by chairs. ASHRAE Transactions 100(1):795-802.
McIntyre, D.A. 1976. Overhead radiation and comfort. The
Building Services Engineer 44:226-232.
McIntyre, D.A. 1978. Preferred air speeds for comfort in
warm conditions. ASHRAE Transactions 84(2):264-277.
McNall, P.E., Jr., and R.E. Biddison. 1970. Thermal and
comfort sensations of sedentary persons exposed to
asymmetric radiant fields. ASHRAE Transactions
76(1):123-136.
McNall, P.E., Jr., J. Jaax, F.H. Rohles, R.G. Nevins, and W.
Springer. 1967. Thermal comfort (thermally neutral)
conditions for three levels of activity. ASHRAE Transactions 73(1):I.3.1-I.3.14.
Melikov, A.K., H. Hanzawa, and P.O. Fanger. 1988. Airflow
characteristics in the occupied zone of heated spaces
without mechanical ventilation. ASHRAE Transactions
94(1):52-70.
Nevins, R.G., and A.M. Feyerherm. 1967. Effect of floor
surface temperature on comfort: Part IV, cold floors.
ASHRAE Transactions 73(2):III.2.1-III.2.8.
Nevins, R.G., K.B. Michaels, and A.M. Feyerherm. 1964.
The effect of floor surface temperature on comfort: Part
II, College age females. ASHRAE Transactions 70:3743.
Nevins, R.G., and P.E. McNall, Jr. 1972. ASHRAE thermal
comfort standards as performance criteria for buildings.
CIB Commission W 45 Symposium, Thermal Comfort
and Moderate Heat Stress, Watford, U.K. (Published by
HMSO London 1973.)
Nielsen, B., I. Oddershede, A. Torp, and P.O. Fanger. 1979.
Thermal comfort during continuous and intermittent
work. Indoor Climate, P.O. Fanger and O. Valbjorn,
eds., Danish Building Research Institute, Copenhagen,
pp. 477-490.
Nilsson, S.E., and L. Andersson. 1986. Contact lens wear in
dry environments. ACTA Ophthalmologica 64:221-225.
Nishi, Y., and A.P. Gagge. 1977. Effective temperature scale
useful for hypo- and hyperbaric environments. Aviation,
Space and Environmental Medicine 48:97-107.
Olesen, B.W. 1985. A new and simpler method for estimating the thermal insulation of a clothing ensemble.
ASHRAE Transactions 91(2b):478-492.
Olesen, B.W. 1977. Thermal comfort requirements for
floors. Proceedings of The Meeting of Commissions B1,
B2, E1 of IIR, Belgrade, pp. 307-313.
Olesen, B.W. 1977. Thermal comfort requirements for floors
occupied by people with bare feet. ASHRAE Transactions 83(2):41-57.
Olesen, S., P.O. Fanger, P.B. Jensen, and O.J. Nielsen. 1972.
Comfort limits for man exposed to asymmetric thermal
radiation. CIB Commission W 45 Symposium, Thermal
Comfort and Moderate Heat Stress, Watford, U.K.
(Published by HMSO London 1973).
26
Olesen, B.W., E. Mortensen, J. Thorshauge, and B. BergMunch. 1980. Thermal comfort in a room heated by different methods. ASHRAE Transactions 86(1):34-48.
Olesen, B.W., M. Scholer, and P.O. Fanger. 1979. Discomfort caused by vertical air temperature differences.
Indoor Climate, P.O. Fanger and O. Valbjorn, eds., Danish Building Research Institute, Copenhagen.
Rohles, F.H., J.E. Woods, and R.G. Nevins. 1974. The effect
of air speed and temperature on the thermal sensations
of sedentary man. ASHRAE Transactions 80(1):101119.
Rohles, F.H., S.A. Konz, and B.W. Jones. 1983. Ceiling fans
as extenders of the summer comfort envelope. ASHRAE
Transactions 89(1a):245-263.
Rohles, F.H., G.A. Milliken, D.E. Skipton, and I. Krstic.
1980. Thermal comfort during cyclical temperature
fluctuations. ASHRAE Transactions 86(2):125-140.
Rohles, F.H., Jr., J.E. Woods, and R.G. Nevins. 1973. The
influence of clothing and temperature on sedentary
comfort. ASHRAE Transactions 79:71-80.
Scheatzle, D.G., H. Wu, and J. Yellott. 1989. Extending the
summer comfort envelope with ceiling fans in hot, arid
climates. ASHRAE Transactions 95(1):269-280.
Schiller, G., E. Arens, F. Bauman, C. Benton, M. Fountain,
and T. Doherty. 1988. A field study of thermal environments and comfort in office buildings. ASHRAE Transactions 94(2):280-308.
Simmonds, P. 1992. The design, simulation and operation of
a comfortable indoor climate for a standard office.
ASHRAE/DOE/BTEC Conference Proceedings, Clearwater Beach, FL.
Simmonds, P. 1993. Thermal comfort and optimal energy
use. ASHRAE Transactions 99(1):1037-1048.
Simmonds, P. 1993. Designing comfortable office climates.
ASHRAE Conference Proceedings, Building Design
Technology and Occupant Well-Being in Temperate Climates, Brussels, Belgium, February.
Simmonds, P. 2000. Using radiant cooled floors to condition
large spaces and maintain comfort conditions. ASHRAE
Transactions 106(1).
Simmonds, P. 1994. Radiant heating and cooling systems.
ASHRAE Transactions 100(2).
Sprague, C.H., and P.E. McNall, Jr. 1971. Effects of fluctuating temperature and relative humidity on the thermal
sensation (thermal comfort) of sedentary subjects.
ASHRAE Transactions 77:183-199.
Wyon, D.P., Th. Asgeirsdottir, P. Kjerulf-Jensen, and P.O.
Fanger. 1973. The effects of ambient temperature
swings on comfort, performance and behavior. Arch.
Sci. Physiol. 27:441-458.
ANSI/ASHRAE STANDARD 55-2004
POLICY STATEMENT DEFINING ASHRAE’S CONCERN
FOR THE ENVIRONMENTAL IMPACT OF ITS ACTIVITIES
ASHRAE is concerned with the impact of its members’ activities on both the indoor and outdoor environment. ASHRAE’s
members will strive to minimize any possible deleterious effect on the indoor and outdoor environment of the systems and
components in their responsibility while maximizing the beneficial effects these systems provide, consistent with accepted
standards and the practical state of the art.
ASHRAE’s short-range goal is to ensure that the systems and components within its scope do not impact the indoor and
outdoor environment to a greater extent than specified by the standards and guidelines as established by itself and other
responsible bodies.
As an ongoing goal, ASHRAE will, through its Standards Committee and extensive technical committee structure,
continue to generate up-to-date standards and guidelines where appropriate and adopt, recommend, and promote those new
and revised standards developed by other responsible organizations.
Through its Handbook, appropriate chapters will contain up-to-date standards and design considerations as the material is
systematically revised.
ASHRAE will take the lead with respect to dissemination of environmental information of its primary interest and will seek
out and disseminate information from other responsible organizations that is pertinent, as guides to updating standards and
guidelines.
The effects of the design and selection of equipment and systems will be considered within the scope of the system’s
intended use and expected misuse. The disposal of hazardous materials, if any, will also be considered.
ASHRAE’s primary concern for environmental impact will be at the site where equipment within ASHRAE’s scope
operates. However, energy source selection and the possible environmental impact due to the energy source and energy
transportation will be considered where possible. Recommendations concerning energy source selection should be made by
its members.
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